I had copied the element called GrowAzureTreeBonemeal and created a new element called GrowGiantPoppyBonemeal, but ran into a problem.
When I bonemeal an Azure Sapling, it spawns in the structure as intended, but when I bonemeal the Poppy flower from vanilla, the structure spawns, but the chunk is not updated visually, which creates "ghost blocks". If I try to walk through the space where the structure should have spawned, the player gets stuck in these "ghost blocks".
Issue comments
After some testing, I can confirm bonemeal used trigger does not support placing structures.
At the moment, the bonemeal event is only run on the server-side, so the client is not notified of structure placement.
Consider using when item right-clicked instead of bonemeal used event and check if item in mainhand is bonemeal.
Wrap your structure spawn events with this procedure blocks:
if NOT "Is provided world remote (client-side)"
(your existing procedure)
You can find "Is provided world remote (client-side)" procedure block in the "World data" procedure blocks section.